lit-element

Declarative Templates

LitElement uses `html` tagged template literals to define templates that are bound to the component's properties. When properties change, the template is efficiently re-rendered.

import { LitElement, html } from 'lit-element';

class MyElement extends LitElement {
  static get properties() {
    return {
      message: { type: String }
    };
  }

  constructor() {
    super();
    this.message = 'Hello, World!';
  }

  render() {
    return html`<p>${this.message}</p>`;
  }
}
customElements.define('my-element', MyElement);

Reactive Properties

Properties can be made reactive using the `@property` decorator. When a reactive property changes, LitElement automatically updates the component's template.

import { LitElement, html, property } from 'lit-element';

class MyElement extends LitElement {
  @property({ type: String }) greeting = 'Hello';

  render() {
    return html`<h1>${this.greeting}, World!</h1>`;
  }
}
customElements.define('my-element', MyElement);

Lifecycle Methods

LitElement provides lifecycle methods such as `firstUpdated`, `updated`, and `disconnectedCallback` for managing the component's lifecycle events.

import { LitElement } from 'lit-element';

class MyElement extends LitElement {
  firstUpdated(changedProperties) {
    console.log('Component first updated!');
  }

  updated(changedProperties) {
    console.log('Component updated with changed properties:', changedProperties);
  }

  disconnectedCallback() {
    console.log('Component removed from the DOM!');
  }
}
customElements.define('my-element', MyElement);